Pages swapped to these disks are compressed and stored in memory itself.
Compressing pages and keeping them in RAM virtually increases its capacity. It can therefore hold more pages of memory in the compressed swap than the amount of actual memory used. Typically it compresses to a 3:1 ratio. This allows more applications to fit in given amount of memory. It is much quicker than swapping to a hard drive. If a system often falls back to swap, this could improve responsiveness.
Installation is simple : open Terminal and copy/paste
sudo apt-get install zram-config
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
Unpacking zram-config (from .../zram-config_0.1_all.deb) ...
Processing triggers for ureadahead ...
Setting up zram-config (0.1) ...
To see if swap has been added :
Total amount is 1/2 of RAM size ( see also file /etc/init/zram-config.conf ).
I previously used a swapfile ( see here ), but replaced it with zram.